向量值的不同组合 [英] the different combinations of a vector's values

问题描述

假设我有一个n个值的向量，我想获取其值的不同组合，例如:如果我有vect = [a，b，c]，我想要的不同组合是:[a，b ，c]，[a，b]，[a，c]，[b，c]，[a]，[b]，[c]

Suppose I have a vector of n values, I want to get the different combinations of its values, for example: if I have vect = [a, b, c] the different combinations that I want are: [a, b, c], [a,b], [a,c], [b,c], [a], [b], [c]

请注意，例如[a，b]与[b，a]相同，因此我不需要同时保留它们.

Note that for example [a,b] is the same as [b,a] so I don't need to keep both of them.

推荐答案

从0到2^vector.size() - 1的计数.如果您的循环变量的第i位为1，则在您的组合中添加vector[i].

Count from 0 to 2^vector.size() - 1. If bit i of your loop variable is 1, include vector[i] in your combination.

vector<char> v;
v.push_back('a');
v.push_back('b');
v.push_back('c');
for (int counter = 0; counter < (1 << v.size()); ++counter)
{
    vector<char> combination;
    for (int i = 0; i < v.size(); ++i)
    {
        if (counter & (1 << i))
            combination.push_back(v[i]);
    }

    // do something with combination
}

如果要排除空集，请从1开始计数.

if you want to exclude the empty set, start counting at 1.

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